Heinrich hackl



July 14, 1931.

H. HACKL MANUFACTURE OF BISULPHITE LIQUOR ANU'DIIAGNESIUK PHOSPHATE Filed March 21, 1929 IN VE NTOR HEINRICH HACKL 67 /I/s azzofneys rv n1 Patented July 14, 1931 UNITED Ns"luariajsv PATENT lOFFICE HEINRICH HACKI., or HEUFELD, GERMANY Mann.FAomnia-E''0F BIS'ULPHITE lLnznroa AND DIMaeivEsi'i/r P'HosPHATE Appnatimn` ala 'Maren 421,'192a'se1-'ia1 No. 348,999, and in Germany March a7, 192s.

"10 ent ,strate 'of the art, is' too expensive. I have invented a new processby which compounds dfimazgnesium and 'of sodium with sulphurous acid may be more cheaply prepared..

' vIt isknown that'solutions`ofcrude phos- *515 phate 'in sulphurus lacid with simultaneous 'or subsequent addition of magnesium sul phate vremoval of 'the ygypsiimv which :is -formed, can be nsed as crude lliquors of monomagne'sium phosphate and magnesium bisulphite with an excess of free sulphurousacid. yAccording to this process dimagnesiumfpho-sphatefcanbe separated from these 'liqfnors'by kthe i addition of magnesium vc"omponnds hav- -I `g5 ing abasic character. The yield of these valuable `phosphate fertilizers I is, however,y very small incomparison with the bisulphite yield, .whichflatter isy composed 'in this process of three quantities. y 'y l f1. 'Before p-recipitation takes place, the whole of the free sulphurous acid contained "in the liquor y"must Vbe yneutralied 'by'a basic Y'magnesium "compound whereby bisulphite is formeel.v 1 l v 2. For every one molec'nleof, phosphoric Vaeid in thepieciptation two'molecules'of bisulphite remain inthe liquor.

` e. `The Calcium eafbonaeeenntfm am o Yph'osl'ahate also passes through the :form 'of 'calcium bisulphite into thei'to'rm of magnesium bisulphite in the inal liquor. Neglecting. the calcium carbonate contained'in the crude phosphatepbut'taking into considera- 45 tion the necessary. excess of free sulphurous acid, the reaction takes place therefore in the following' way:

the wholeofthe free siilphurous acidescapes,

assuch,'jafter which, o n further raising thel temperature, diinagnesiuin phosphate is'pre- M5 Vcipit'ated with, the evolution of lsulphurons acid from the'corresponding quantity of'bti- "sulphite' and there remains, to the end of the boiling, a precipitate which consists substan'- tially of dimagnesium'phosphate`and a'liquor 70 of magnesium bisulphite but in much more `fa`vo1irable relative proposition than in the process known hitherto. place in the following way vIn accordance with A'this invention, therefore, less than half the quantity of bisulphite is obtained with the same quantity ofdimag- 80 nesinm phosphate as compared with the known process. Therefore, by the'new proc* ess more than double the quantity of valuable phosphate 'fertilizer is made for an equal quantity of bisulphite made by the old proc- '85 esses. vThe provision of a basic'magnesium compound for precipitation is not required anda great portion of the sulphurous acid canbe used in a concentrated form for the ysolution 'of fresh1 phosphate. 90

It was not to be expected that magnesium bisulphite would be stable when heated in the presence of dimagnesium phosphate, because the diphosphate has the property when boiled with water, of splitting up into trihos Jhate and mono hos )hate' neither was .P P

it to be expected that, by suitably selecting the conditions of solution, a bisulphite liquor would be obtained whichvwould correspond approximately, as regards its sulphite content to the lime liquors commonly employed in the cellulose industry.

The present process permits of phosphates which, on account of the large amount of calcium carbonate they contain, are only of small value, being treated to form a fertilizer of high percentage, as the calcium carbonate Content does not function asa diluent in the solid final product but figures as magnesium bisulphite in the final liquor. V

It has also been found that a portion of the magnesium sulphate may be replaced by sodium sulphate, anda sodium bisulphite liquor obtained in addition to dimagnesium phosphate or one mixed with magnesium bisulphite.

The bisulphite liquors are free from lime.

EmampZe.-165O parts kieserite are dissolve din 16,500 parts water and 1500 parts phosphate Kalaa-es-Djerda, containing approximately 122/370 CaCO3 and approximately 57% CaSPZOS together with the minor proportions of other ingredients, are added to the solution. rlhe entire mass is treated with gaseous SO2 (sulfur-dioxide), while being kept agitated, whereby a liquor of about 16o B. is obtained which is separated from the gypsum produced and then boiled. The boiling causes about 75% of the amount of S02 contained in the solution to be evolved which, after being cooled down, are again utilized for the dissolving ot aI fresh mixture of kieserite, phosphate and water, while the remaining about 25% SO2 retained in the liquor, are replaced by fresh SO2-gases.

After boiling for about 1 to 1% hours the phosphoric acid has been almost completely precipitated as dimagnesium-phosphate. This precipitate, after having been separated from the liquor and after having been dried contains about 33% PO5 which are entirely soluble in citric acid, while the liq- 'uor constitutes a solution of magnesium-bisulphite of sutlicient strength to be i vailable for boiling the pulp either directly or after 'having been charged with free SO2.

The accompanying How sheet illustrates diagrammatically the process described.

I claim 1. The method of producing lime free bisulphite liquors comprising the steps of 4adding magnesium sulphate to a solution ot crude phosphate in sulphurous acid, separat- 'ing the resulting liquid and solid matters,

precipitating dimagnesium phosphate from the said liquid by boiling the same and separating such dimagnesium phosphate from the linal bisulphite liquor.

2. The method of producing lime free bisulphite liquors comprising the steps of adding sulphurous acid and magnesium sulphate to crude phosphate, separating the resulting liquid and solid matters, heating the liquid to a temperature such that dimagnesium phosphate is precipitated and withdrawing the final bisulphite liquor from the dimagnesium phosphate.

3. The method of producing lime free bisulphite liquors, comprising the steps of adding magnesium sulphate and sodium sulphate to a solution of crude phosphate in sulphurous acid, separating the resulting liquid and solid matters, precipitating dimagnesium phosphate from the Vsaid liquid by boiling the same and separating such dimagnesium phosphate from the bisulphite liquor. f

4. The method of producing lime free bisulphite liquors, comprising the steps of adding sulphurous acid, magnesium sulphate and sodium sulphate to crude phosphate, separating the resulting liquid and solid matters, heating the liquid to a temperature such that dimagnesium phosphate is precipitated and withdrawing the linal bisulphite liquor from the dimagnesium phosphate.

5. The method of producing lime free bisulphite liquors, comprising the steps of adding Vmagnesium sulphate to a solution of crude phosphate in 'sulphurous acid, separat- Ving the resulting liquid and solid matters, precipitating dimagnesium phosphate from the said liquid by boiling the same under reduced pressure and separating such dimagnesium phosphate from the final bisulphite liquor. f

6. The method of producing lime free bisulphite liquors, comprising the steps of adding sulphurous acid and magnesium sulphate to crude phosphate, separating the resulting liquidand solid matters, heating the liquid under reduced pressure to a temperature lsuch that dimagnesiumy phosphate is precipitated and withdrawing the final bisulphite liquor from the dimagnesium phosphate.

7. The method of producing lime free bisulphite liquors, comprising the steps of adding magnesium sulphate and sodium sulphate to a solution of crude phosphate in sulphurous acid, separating the resulting liquid and solid matters, precipitating dimagnesium .phosphate from the said liquid by boiling the same under reduced pressure and separating such dimagnesium phosphate from the final ist arating the resulting liquid and solid Inatters, heating the liquid under reduced pressure to a temperature such that dimagnesium phosphate is precipitated and withdrawing the final bisulphite liquor from the dimagnesium phosphate.

9. In the preparat-ion of bisulphite liquors with simultaneous production of ldimagnesium phosphate the method of increasing the yield dimagnesium phosphate consisting in subjecting a crude liquor containing monomagnesium phosphate and magnesium hisulphite to a temperature suicient at the prevailing pressure to. cause the dimagnesium phosphate to precipitate from the liquor.

10. In the preparation of hisulphite liquors With simultaneous production of dimagnesium phosphate, the method of increasing the yield of dimagnesium phosphate consisting in subjecting a crude liquor containing monomagnesum phosphate, magnesium bisulphite and sodium bisulphite to a temperature sufficient at the prevailing pressure to cause dimagnesium phosphate to precipitate from the liquor.

In testimony whereof I have signed by name to this specification.

HEINRICH HACKL. 

